1. Field of the Invention
This invention is related to an optical switching apparatus for use in optical networks for voice and data communications. In particular, the present invention is directed to an optical switching device with divergence correction of light beams which propagate in a waveguide of an optical switching apparatus.
2. Description of the Related Art
The strong growth of optical networks for voice and data communication has created a huge demand for high data rate information transfer capabilities. To enable such transfer capabilities, dense wavelength division multiplexing (DWDM) technology has been developed which allows transfer of multiple wavelength light beams over a single optical fiber leading to data transfer rates up to 40-100 Gb/s. High speed switching and routing devices comprise the core elements of the optical networks and allow dynamic control of the data traveling over the optical network. High data transmission rates impose significant demands on the functionality of the switching devices.
Optical cross-connect space division switches based on optic-electro (OE) deflection of the light beam have great potential for use in high speed optical networks. The basic requirements for such devices are the need for extremely fast switching time and the capability to handle a large number of input and output channels, e.g., up to 4000xc3x974000 by the year 2003. Reliability and cost are also important design factors for optical switching devices. Existing optical switching devices which employ signal conversion from optical into electrical and back into optical do not satisfy the anticipated requirements for such devices.
Switching matrixes having very low switching times can be designed to connect a very large number of input and output (I/O) ports. Such switches may be built from an assembly of simple digital optical switches where each can redirect one input signal into two possible output ports. However, optical cross-connect switching elements are more useful for large-scale implementations. These devices require large-scale monolithic switch arrays to perform switching functions. Although, the principles used in optical cross-connect switching based on light beam deflection is well known, a robust, reliable, low cost and extendable integration process for such type of switching device is not available.
Currently, the main optical switching products on the market (e.g. Lucent""s Lambda-router) are based on MEONIS technology, which employs rotating micro-mirrors to deflect light. However, these optical switching devices are not very reliable due to the large number of moving parts, and the limitation on the switching time caused by the mechanics of the mirrors. It is desirable to improve the reliability of the moving parts of the optical switching devices and to overcome the limitation of the switching time in these devices due to the mechanics of the micro-mirrors.
There are several other optical switching technologies which have been proposed but which are still not well represented in the market due to various technological and economic difficulties. Such optical switching technologies include by way of example: the bubble switch from Agilent Technologies Inc., switches based on liquid crystals, and thermo-optic and electro-optic (EO) effects, etc. Most of these devices are still in the RandD stage. Some of these technologies, including EO switches, may be applicable for high speed, low cost, high reliability, and high I/O port count products.
Existing EO switch designs, however, require at least two paths from the switch, and a channel waveguide for each path in order to transmit a light input without divergence. Such channel waveguides require a relatively large amount of space in the switching device. As more channels are incorporated into the optical switching device, much more space for the channel waveguides is required therein.
Therefore, there is a need for an improved optical switching device which does not require as much space therein. There is a further need for an improved optical switching device with divergence correction of the light beams transmitted through the device.
Embodiments of the present invention provide: a compact optical switching device with improved divergence correction of the light beams which propagate in an optical switching device without having a channel waveguide. The optical switching device of the present invention includes EO material sandwiched by electrodes. In accordance with an aspect of the present invention, the EO material has a lens portion for collimating light.
The optical switching apparatus of the present invention enables a large number of channels to be accommodated within the optical switching apparatus.
These features together with the various ancillary provisions and features which will become apparent to those skilled in the art from the following detailed description, are attained by the optical switching apparatus and method of the present invention, preferred embodiments thereof being shown with reference to the accompanying drawings, by way of example only, wherein: